c++ - 在 Singleton 设计模式的情况下，我们如何使析构函数私有(private)化？

Question

我正在多线程环境中创建一个单例类，任何线程都可以删除单例对象。我想保护这个。我在某处读到可以避免这个问题，我们可以将析构函数设为私有(private)并提供销毁方法。我们该怎么做？示例代码将有所帮助..

提前致谢。

Answer 1

class Singleton; // forward declaration

Singleton * s = NULL; // global object available to all threads

// Place this class in a location unavailable to all threads except Main thread
class ManageSingleton
{
    public:
        static void DestroySingleton(Singleton * s)
        {
            delete s;
        }
}

class Singleton
{
    friend class ManageSingleton;
    protected:
        ~Singleton() {}
};

void main()
{
    s = new Singleton;
    while (...)
    {
       // other threads access Singleton object until program is finished 
    }

    // Program is now finished; destroy Singleton object
    ManageSingleton::DestroySingleton(s);
}